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NITED STATES PATENT Fi -ICE;

MANUFACTURE OF BOLTS.

SPECIFICATION forming part of Letters Patent No. 252,661, dated January 24, 1862.

Application filed December 2, 1881.

To all whom it may concern:

Be it known that I, CHARLES HALL, of the city and State of New York,l1ave invented an Improvement in the Manufacture of Bolts, of which the following is a specification.

Bolts have been manufactured by machines in which there is a plunger that upsets the iron rod and spreads the same into the cavity of the die. A machine of this character may be seen in Letters Patent No. 88,783, granted April 13, 1869, and No. 44,623, granted October 11, 1864. p

In bolt-machines the head can bemade much more uniform in measurement where the solid die is used than it can with a divided die, because particles of iron get' in between the parts of the die and prevent them closing; but

there is great difficulty in keeping the punch or plunger in the proper condition. Heretofore the effort has been to fit the plunger to the die as tightly as possible, both in solid and divided the machines, so that the head will come out of the die in a finished condition; but in practice it is found that the duties performed by the punch and die are so severe that the steel at the end of the punch wears away and cracks, and it is alsoimpossible to feed in exactly the same quantity of iron for each head. Hence in some instances the die is not filled and the head is imperfect, or else the metal is in excess, and a very thin film or fin is thrown out between the punch and the die, and this film breaks off andavedges in between the surfaces and prevents the proper movement of the punch or plunger, scratches and strains the die, and renders the machine unreliable in use.

My invention is made for the purpose of insuring a perfectly full head, for discharging the surplus material, for lessening wear upon the punch or plunger and the die, for preventing the lodgment of any particles of-metal between the plunger and the die, and forincreasing the length of time that the plunger and die can be used without requiringto be ground or repaired. I

In the drawings, Figure 1 represents a section of the holding -jaws, the die, and the punch. Fig. 2 is a perspective view, representing a bolt-head as it comes out of the machine, and Fig. 3 is a similar "iew ol'the' bolthead as finished off for sale.

(No model.)

The holding-jaws a, the die I), the cutter c, and v the means for supporting and operating such devices are to be of any desired charaeter such, for, instance, as those shown in either of the foregoing Letters Patent. The die I) is to be of the size of the exterior measurement of the bolt-head, and it is preferably of one piece of steel. 1

The punch or plunger 6 is to be operated by a cam or a crank, as in aforesaid Letters Patcut; but instead of the same fitting the die accurately ,I make such plunger purposely smaller than the interior of the die and round the edges slightly. The object of this is, first,

to lessen the expense of making the plunger;

sec0nd,t0 lessen the friction and wear between the plunger and the die; third, to leave a space between parts for the surplus metal to be discharged in the form of a tin thrown out around the head of the bolt between the plunger and the die, such tin being of sufficient thickness to prevent it being broken when the plunger withdraws from thchead. The result of this mode of making the bolt-head is that the bar or rod can be fed in sufficiently to insure the required quantity of material for the head without the risk of damage to the dies and machine by too much iron in the head, and there is no risk of the head not being formed up perfectly, for the metal will fill into all the angles of the die before there is'any fin thrown out, because the surplus metal will not be thrown out as a fin until the whole ofthe head has been exposed to a pressure equal to that required to make theiron pass into the narrow space between the plunger and the die. By. this means a perfect head is insured and an escape for surplus metal provided. After the bolts have been forged, the fin is to be cut off or removed by a suitable cutter or millingtool. It is usually preferable to employ a cutter thatv will round the upper corners of the bolt slightly and shape the same as represented in Fig. 3.

An emery-wheelor grinding tool may be used for smoothing the head or cutting off the tin.

The bolts may be heated to give a blue color to the metal at the end of thehead.

The rounded edges of the plunger prevent any tendency of the plunger to cut or break the tin and the surface of the plunger remains smooth and flat, whereas in the ordinaryplunger the metal around the sharp edgesis pressed inwardly and forms a slight; ridge around the face of the plunger. Hence there will be a corresponding depression or groove around the 5 top of the head.

I claim as my inventi0n 1. In a machine for forging bolt-heads, a die having a hole of the size and shape of the head, in combination with a plunger that is designedly made sufficiently smaller than the die'for a fin to be t rown out around the head for the discharge of the surplus metal from the die, substantially as set forth.

2. The method herein specified of making 15 bolt-heads, consisting in feeding into the machine more of the rod or bar than is required for forming the head, pressing up the bolthead in the die by means of a plunger, forming a fin around the bolt-head of the surplus metal, and removing such fin and finishing the top of the bolt-head by cutting or grinding after the bolt is delivered from the machine,'substantially as set forth.

Signed by me this 30th day ofNovember, A. 1). 1881.

CHAS. HALL. Witnesses:

GEO. T. PINCKNEY, WILLIAM G. MOTT. 

